WO1998014118A1 - Photoacoustic breast scanner - Google Patents

Photoacoustic breast scanner

Info

Publication number
WO1998014118A1
WO1998014118A1 PCT/US1997/017832 US9717832W WO9814118A1 WO 1998014118 A1 WO1998014118 A1 WO 1998014118A1 US 9717832 W US9717832 W US 9717832W WO 9814118 A1 WO9814118 A1 WO 9814118A1
Authority
WO
Grant status
Application
Patent type
Prior art keywords
tissue
acoustic
pressure
electromagnetic
transducer
Prior art date
Application number
PCT/US1997/017832
Other languages
French (fr)
Inventor
Robert A. Kruger
Original Assignee
Optosonics, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

Links

Classifications

    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Detecting, measuring or recording for diagnostic purposes; Identification of persons
    • A61B5/0093Detecting, measuring or recording by applying one single type of energy and measuring its conversion into another type of energy
    • A61B5/0095Detecting, measuring or recording by applying one single type of energy and measuring its conversion into another type of energy by applying light and detecting acoustic waves, i.e. photoacoustic measurements
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Detecting, measuring or recording for diagnostic purposes; Identification of persons
    • A61B5/0059Detecting, measuring or recording for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
    • A61B5/0082Detecting, measuring or recording for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence adapted for particular medical purposes
    • A61B5/0091Detecting, measuring or recording for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence adapted for particular medical purposes for mammography
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Detecting, measuring or recording for diagnostic purposes; Identification of persons
    • A61B5/05Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radiowaves
    • A61B5/0507Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radiowaves using microwaves or terahertz waves
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Detecting, measuring or recording for diagnostic purposes; Identification of persons
    • A61B5/43Detecting, measuring or recording for evaluating the reproductive systems
    • A61B5/4306Detecting, measuring or recording for evaluating the reproductive systems for evaluating the female reproductive systems, e.g. gynaecological evaluations
    • A61B5/4312Breast evaluation or disorder diagnosis
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/42Details of probe positioning or probe attachment to the patient
    • A61B8/4272Details of probe positioning or probe attachment to the patient involving the acoustic interface between the transducer and the tissue
    • A61B8/4281Details of probe positioning or probe attachment to the patient involving the acoustic interface between the transducer and the tissue characterised by sound-transmitting media or devices for coupling the transducer to the tissue
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Detecting, measuring or recording for diagnostic purposes; Identification of persons
    • A61B5/72Signal processing specially adapted for physiological signals or for diagnostic purposes
    • A61B5/7235Details of waveform analysis
    • A61B5/7239Details of waveform analysis using differentiation including higher order derivatives

Abstract

Methods and apparatus for measuring and characterizing the localized electromagnetic wave absorption properties of biologic tissues (12) in vivo, using incident electromagnetic waves to produce resultant acoustic waves (26). Multiple acoustic transducers (33) are acoustically coupled to the surface of the tissue for measuring acoustic waves produced in the tissue when the tissue is exposed to a pulse of electromagnetic radiation. The multiple transducer signals are then combined to produce an image of the absorptivity of the tissue, which image may be used for medical diagnostic purposes. In specific embodiments, the transducers are moved to collect data from multiple locations, to facilitate imaging. Specific arrangements of transducers are illustrated. Also, specific mathematical reconstruction procedures are described for producing images from transducer signals.

Description

PHOTOACOUSTIC BREAST SCANNER

This application is a 35 USC § 120 continuation of U.S. Serial No. 08/719,736.

Background of the Invention

The present invention relates to imaging properties of tissue based upon differential

absorption of electromagnetic waves in differing tissue types by photo-acoustic techniques.

It is well established that different biologic tissues display significantly different interactions with electromagnetic radiation from the visible and infrared into the microwave region of the electromagnetic spectrum. While researchers have successfully quantified these interactions in vitro, they have met with only limited success when attempting to localize sites of optical interactions

in vivo. Consequently, in vivo imaging of disease at these energies has not developed into a clinically

significant diagnostic tool.

In the visible and near-infrared regions of the electromagnetic spectrum, ubiquitous

scattering of light presents the greatest obstacle to imaging. In these regions, scattering coefficients

of 10-100 mm"1 are encountered. Consequently, useful numbers of unscattered photons do not pass

through more than a few millimeters of tissue, and image reconstruction must rely on multiply-

scattered photons. While efforts persist to use visible and infrared radiation for imaging through thick

tissue (thicker than a few centimeters), clinically viable imaging instrumentation has not been

forthcoming.

In the microwave region (100-3000 MHZ), the situation is different. Scattering is not as important, since the wavelength (in biologic tissue) at these frequencies is much greater than the

"typical" dimension of tissue inhomogeneities (« lμm). However, the offsetting effects of diffraction and absorption have forced the use of long wavelengths, limiting the spatial resolution that can be

achieved in biologic systems. At the low end of the microwave frequency range, tissue penetration is good, but the wavelengths are large. At the high end of this range, where wavelengths are shorter,

tissue penetration is poor. To achieve sufficient energy transmission, microwave wavelengths of

roughly 2-12 cm (in tissue) have been used. However, at such a long wavelength, the spatial resolution that can be achieved is no better than roughly V2 the microwave length, or about 1-6 cm.

In vivo imaging has also been performed using ultrasound techniques. In this technique, an acoustic rather than electromagnetic wave propagates through the tissue, reflecting

from tissue boundary regions where there are changes in acoustic impedance. Typically, a

piezoelectric ceramic chip is electrically pulsed, causing the chip to mechanically oscillate at a frequency of a few megahertz. The vibrating chip is placed in contact with tissue, generating a narrow beam of acoustic waves in the tissue. Reflections of this wave cause the chip to vibrate, which vibrations are converted to detectable electrical energy, which is recorded.

The duration in time between the original pulse and its reflection is roughly

proportional to the distance from the piezoelectric chip to the tissue discontinuity. Furthermore,

since the ultrasonic energy is emitted in a narrow beam, the recorded echoes identify features only

along a narrow strip in the tissue. Thus, by varying the direction of the ultrasonic pulse propagation, multi-dimensional images can be assembled a line at a time, each line representing the variation of

acoustic properties of tissue along the direction of propagation of one ultrasonic pulse.

For most diagnostic applications, ultrasonic techniques can localize tissue

discontinuities to within about a millimeter. Thus, ultrasound techniques are capable of higher spatial resolution than microwave imaging.

The photoacoustic effect was first described in 1881 by Alexander Graham Bell and

others, who studied the acoustic signals that were produced whenever a gas in an enclosed cell is

illuminated with a periodically modulated light source. When the light source is modulated at an audio frequency, the periodic heating and cooling of the gas sample produced an acoustic signal in

the audible range that could be detected with a microphone. Since that time, the photoacoustic effect has been studied extensively and used mainly for spectroscopic analysis of gases, liquid and solid

samples.

It was first suggested that photoacoustics, also known as thermoacoustics, could be

used to interrogate living tissue in 1981, but no subsequent imaging techniques were developed. The

state of prior art of imaging of soft tissues using photoacoustic, or thermoacoustic, interactions is best summarized in Bowen U.S. Patent No. 4,385,634. In this document, Bowen teaches that ultrasonic signals can be induced in soft tissue whenever pulsed radiation is absorbed within the

tissue, and that these ultrasonic signals can be detected by a transducer placed outside the body.

Bowen derives a relationship (Bowen's equation 21) between the pressure signals p(z,t) induced by

the photoacoustic interaction and the first time derivative of a heating functions, S(z,t), that

represents the local heating produced by radiation absorption. Bowen teaches that the distance between a site of radiation absorption within soft tissue is related to the time delay between the time when the radiation was absorbed and when the acoustic wave was detected.

Bowen discusses producing "images" indicating the composition of a structure, and

detecting pressure signals at multiple locations, but the geometry and distribution of multiple transducers, the means for coupling these transducers to the soft tissue, and their geometrical relationship to the source of radiation, are not described. Additionally, nowhere does Bowen teach how the measured pressure signals from these multiple locations are to be processed in order to form

a 2- or 3 -dimensional image of the internal structures of the soft tissue. The only examples presented are 1 -dimensional in nature, and merely illustrate the simple relationship between delay time and

distance from transducer to absorption site. Summary of the Invention

The present invention improves upon what is disclosed by Bowen in two ways. First,

the present invention uses multiple transducers to collect photoacoustic signals in parallel, and then

combines these signals to form an image. This approach represents a significant advance over Bowen

in that the use of multiple, parallel transducers, substantially reduces the time needed to collect

sufficient information for imaging. Furthermore, while Bowen fails to suggest methodologies for creating multidimensional images, the present invention provides specific methodologies for reconstructing multidimensional images of internal tissues through the combination of multiple

pressure recordings. As part of achieving these advances over Bowen, the present invention details the frequencies that might be used, the size of the multiple transducers, their geometrical relationship

to one another and to the tissue, and structures for coupling sensors to the tissue.

Specifically, in one aspect, the invention provides a method of imaging tissue

structures by detecting localized absorption of electromagnetic waves in the tissue. An image is

formed by irradiating the tissue with a pulse of electromagnetic radiation, and detecting and storing

resultant pressure waveforms arriving at the acoustic sensors. Multiple detected pressure waveforms are then combined to derive a measure of the extent to which pressure waveforms are originating at

a point distant from the acoustic sensors. This step can then be repeated for multiple points to

produce an image of structures in the tissue.

In a disclosed particular embodiment, the multiple pressure waveforms are combined to form an image at a point by determining a distance between the point and a pressure sensor, and

then computing a value related to the time rate of change in the pressure waveform, at a time which is a time delay after the pulse of electromagnetic radiation ~ this time delay being equal to the time

needed for sound to travel through the tissue from the point to the pressure sensor. This process, determining a distance and time delay, and then computing a value for time rate of change, is

repeated for each additional pressure sensor and its pressure waveform, and the computed values are

accumulated to form the measure of the pressure waveforms originating at the point. These point measurements may then be collected into a multi-dimensional image.

In one specific embodiment, the pressure sensor signal is processed by appropriate

electrical circuitry so that the electrical output of the sensor is representative of the time rate of

change of the pressure waveform. As a result, the value representing the time rate of change of pressure is directly available from the sensor output. To create an appropriate output, delayed

versions of the output of the sensor are combined with the output of the sensor, which produces an electrical output representative of the time rate of pressure change.

In an alternative embodiment discussed below, a measure of pressure waveforms

originating at a point, is generated by computing a value related to a sum of the pressure waveform

detected by the acoustic transducer over the time period ~ where again the time period begins simultaneous with the electromagnetic irradiating pulse, and has a duration equal to the time needed

for sound to travel through the tissue from the point to the pressure sensor. These steps can then be

repeated for additional pressure sensors and their waveforms, and the results accumulated as discussed above to form the measure of pressure waveforms originating at the point.

In either approach, it is useful to multiply the computed time rate of change, or computed time period sum, of an acoustic transducer signal, by a factor proportional to the time delay used to produce the value. Doing so compensates for the diffusion of acoustic energy radiated

from the point as it travels through the tissue to the transducer.

In apparatus for carrying out these imaging methods, the sensors are positioned on a surface and relatively evenly spaced across the surface so as to, in combination, produce sharp multi- dimensional images through the tissue. To reduce the number of sensors required, the sensors may

be moved to multiple positions while producing an image. Specifically, while the sensors are in a first position, the tissue is irradiated and the pressure waveforms from the sensors are recorded. Then the sensors are moved to a second position and the irradiation and waveform storage are repeated. In

this way, each sensor can be moved to a number of positions to generate multiple waveforms. All of

the stored waveforms can then be combined to generate an image of the tissue.

The sensors may be positioned on a plane and moved in a rectilinear fashion, in which case the electromagnetic irradiation source may be moved in synchrony with the sensors.

Alternatively, the sensors may be positioned on a spherical surface (having a center of curvature

approximately in the center of the tissue region to be imaged) which is rotated to multiple positions.

In this latter case, the sensors can be advantageously positioned on the spherical surface along a spiral path, so that rotation of the sensors produces a relatively even distribution of sensor locations

across the spherical surface.

To enhance acoustic coupling to the tissue, the sensors may be immersed in an acoustic coupling media, having an acoustic characteristic impedance which is substantially similar to

that of the tissue to reduce reflections of acoustic waves impinging into the media from the tissue. A flexible film may be used to contain the acoustic coupling media, so that the tissue can be pressed upon the flexible film to couple acoustic waves from the tissue into the acoustic coupling media.

Similarly, the electromagnetic radiation source may be immersed in an

electromagnetic coupling media having an electromagnetic characteristic impedance which is

substantially similar to that of the tissue to reduce reflections of electromagnetic waves impinging into the tissue from the electromagnetic coupling media. Here again, a flexible film is used to couple electromagnetic waves from the electromagnetic coupling media into the tissue. In one particular embodiment, both the electromagnetic radiation source and the acoustic transducers are immersed in the same coupling media, and the coupling media has a

characteristic acoustic and electromagnetic impedance which is substantially similar to that of the tissue.

The electromagnetic radiation may be laser-generated radiation in the ultraviolet,

visible or near-infrared band, light generated by a Xenon flash lamp, or microwave frequency radiation from a microwave antenna such as a coil. In the latter case, a microwave frequency of four

hundred and thirty-three or nine hundred and fifteen MHZ may be advantageous since these

frequencies are FCC approved and fall within a frequency band in which malignant and normal tissue exhibit substantially different absorptivities.

The above and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and the description thereof.

Brief Description of the Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the

invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the invention.

Fig. 1 is a functional block diagram of a photoacoustic scanner for scanning breast tissue in accordance with a first embodiment of the present invention;

Fig. 2 is a top view of one embodiment of a transducer array for the scanner of Fig. 1;

Fig. 3 illustrates the waveforms produced in the scanner of Fig. 1;

Fig. 4 illustrates the spatial response of pressure transducers used in a photoacoustic scanner such as that of Fig. 1; Fig. 5 is a second embodiment of a photoacoustic breast scanner in accordance with the present invention, using a laser or flash tube source of electromagnetic energy;

Fig. 6 is an embodiment of a transducer array and electromagnetic source for a scanner such as that of Fig. 1, configured for rectilinear scanning motion;

Fig. 7 is an embodiment of a transducer array and electromagnetic source for a

scanner such as that of Fig. 1, configured for rotational scanning motion;

Fig. 8 is a particular embodiment of a rotationally scanning transducer array, formed on a spherical surface, illustrating the positioning of the transducers on the spherical surface of the

array;

Fig. 9 illustrates the axial alignment of the transducers on the spherical surface of the

array of Fig. 8;

Fig. 10 illustrates the locus of transducer positions brought about through rotational

scanning of the array of Fig. 8;

Figs. 11 A and 1 IB are a third embodiment of a photoacoustic breast scanner in accordance with the present invention, using an acoustic coupling tank configured to permit

placement of a rotationally scanning acoustic transducer array in close proximity to a human breast;

Fig. 12 is a circuit diagram of an integral transducer signal amplifier for a

photoacoustic breast scanner;

Fig. 13 is a fourth embodiment of a photoacoustic breast scanner in accordance with

the present invention, using an acoustic coupling tank configured to permit a rotationally scanning

acoustic transducer array to surround a human breast;

Fig. 14 illustrates the geometric relationships involved in the reconstruction methodologies used to generate a tissue image; Fig. 15 illustrates a reconstruction methodology for forming a tissue image from acoustic transducer signals;

Fig. 16 is an experimental apparatus used to generate an image of an absorption phantom generally in accordance with the methodology of Fig. 15, and Fig. 17 is the image created

therefrom;

Fig. 18 illustrates a second reconstruction methodology for forming a tissue image from acoustic transducer signals;

Fig. 19 illustrates the ideal impulse response of a transducer which produces an

electrical output signal indicative of the first temporal derivative of an incident pressure signal;

Fig. 20 illustrates a simulated actual impulse response and a methodology for

converting this impulse response to an approximation of the ideal response illustrated in Fig. 19; and

Fig. 21 is a circuit diagram of a circuit for performing the conversion methodology of Fig. 20.

Detailed Description of Specific Embodiments

Fig. 1 illustrates a photoacoustic breast scanner 10 in accordance with one embodiment of the present invention, which displays several key elements for successful photoacoustic scanning of the female human breast.

A human breast 12 is compressed between two coupling tanks 14, 16. Coupling tank

14 contains fluid or semi-solid media 18 having dielectric properties which are close to that of "average" breast tissue at the microwave (or radio wave) frequencies used to stimulate photoacoustic

emission within the breast 12. Examples would be salinated water, alcohol or mineral oil. The media

18 is contained within tank 14 by a flexible sheet 19, for example of polyethylene, on the surface of the tank coupled to the breast 12. Sheet 19 ensures good mechanical contact between the tissue of breast 12 and the media 18 in tank 14.

Within the top coupling tank is a microwave antenna 20. A microwave generator 22,

i.e., a source of pulse microwave or radio wave energy, is coupled to antenna 20 through a transmission line 24. (One suitable microwave generator is a Hewlett-Packard model 8657B tunable generator, coupled to a 200 Watt RF amplifier available from AMP Research.) Antenna 20 is large

enough to irradiate all or a large fraction of the breast volume to be imaged. A cylindrically-shaped coil antenna, three to nine inches in diameter would be suitable. Further details on waveguides which

can be used as microwave radiators can be found in Fang et al., "Microwave Applicators for Photoacoustic Ultrasonography", Proc. SPIE 2708: 645-654, 1996, which is incorporated by

reference herein in its entirety.

The purpose of dielectric coupling media 18 and sheet 19 is to improve the

penetration of the microwave energy into the breast tissue. Because breast 12 is compressed against

the surface of tank 14, there is a continuous interface between coupling media 18 and the tissue of breast 12, uninterrupted by air gaps. An air gap, or any other physical discontinuity having a corresponding discontinuity in dielectric properties, will cause a large fraction of the microwave

energy to reflect away from the interface (and thus away from the surface of the breast), rather than

penetrate into the breast. By matching the dielectric properties of the breast and media 18, and eliminating air gaps, such discontinuities are reduced, improving microwave penetration into breast

12.

As noted above, microwave generator 22 delivers short-duration pulses of radiation

to breast 12. These bursts should last anywhere from 10 nanoseconds to one microsecond, e.g., 0.5

microseconds. Each radiation burst causes localized heating and expansion of the breast tissue exposed to the microwave energy. Tissue heating and expansion will be greatest in those regions of the breast tissue which are most absorptive of the microwave energy. Ifa region of tissue within breast 12 (e.g., a tumor) is particularly more absorptive than the surrounding tissue, the region will

expand relatively more rapidly and extensively than the surrounding tissue, creating an acoustic wave

which will propagate through the tissue. These acoustic waves are manifested as longitudinal

pressure waves, containing acoustic frequencies ranging from very low frequencies to approximately

the reciprocal of the electromagnetic pulse length. For a one-half microsecond irradiation pulse, this maximum acoustic frequency would be 2 million cycles per second, or two megaHertz (MHZ).

Any of several different microwave frequencies may be used, but frequencies in the

range of 100-1000 MHZ are likely to be particularly effective. At these frequencies, energy

penetration is good, absorption is adequate, and differential absorption between different types of

tissue, e.g. fat and muscle, is high. It has also been reported that the ratio of absorbed energy in cancerous relative to normal breast tissue is enhanced in this frequency range, peaking at 2-3

between about 300-500 MHZ. (See, e.g., Joines, W.T. et al, "The measured electrical properties of normal and malignant human tissues from 50-900 MHZ", Medical Physics. 21(4):547-550, 1994.)

The frequency of 433 MHZ, specifically, has been approved by the FCC for use in hyperthermia

treatments, and accordingly is available and may be used in photoacoustic imaging in accordance with the present invention. Imaging might also be performed at the FCC approved frequency of 915

MHZ. Furthermore, it has been reported that the electrical conductivity of malignant tissue and

normal tissue may vary by a factor of fifty. Accordingly, low frequency electromagnetic radiation

could also be used to stimulate varied energy absorption and acoustic responses in tissue.

Fig. 1 illustrates the acoustic wavefronts 26 produced by electromagnetic irradiation of three absorptive regions 28 within the breast 12. It will be understood that the acoustic waves produced by regions 28 are omnidirectional; however, for clarity only those wavefronts directed toward coupling tank 16 have been illustrated. These acoustic waves travel through the tissue at a

velocity of sound propagation vs which is approximately 1.5 mm/μs.

Coupling tank 16 is filled with media 29 having an acoustic impedance and velocity of sound propagation which are close to that of a "typical" human breast. Distilled and deionized water is an effective media for this purpose. Media 29 is retained within tank 16 by a thin sheet 30, such as

polyethylene. Breast 12 is compressed against sheet 30, thus ensuring good mechanical coupling

from breast 12 to media 29 within tank 16, and allowing acoustic energy to freely pass from breast

12 into tank 16. As with sheet 19 for tank 14, good mechanical coupling through sheet 30 and the

similar acoustic characteristics of breast 12 and media 29 enhances transmission of acoustic signals

out of breast 12 and into media 29 and reduces acoustic wave reflections at the surface of breast 12.

An array 32 of N acoustic transducers is located in tank 16. Several useful array

geometries are discussed herein and can be used successfully in the embodiment of d be at least about two inches across, and might for some applications be as large as twelve inches across. The transducers should be evenly spaced across the array. Fig. 2, for example, is a view illustrating an essentially planar array 32, approximately three inches square, bearing forty-one individual

transducers 33 which can be used as the transducer array 32 in tank 16 of Fig. 1. Other arrangements

of transducers will be discussed below.

Transducers in array 32 detect acoustic pressure waves that are induced within the

breast by the short irradiation pulse, and travel from emission sites (e.g., regions 28) at the velocity

of sound in tissue. The transducers are fabricated so as to be most sensitive to sonic frequencies just

below the maximum frequency stimulated by the irradiation pulse noted above. The N transducers in array 32 are coupled through N electronic signal lines 34 to a computer circuit 36. Computer 36 is further connected through a control line 38 to activate

microwave generator 22 to produce a pulse of microwave energy. Following each pulse of radiation, the time-dependent, acoustic pressure signals recorded by each of the N transducer elements are

electronically amplified, digitized and stored within computer 36. The recorded pressure signal from transducer /' will be referenced hereafter as/?,(t).

For sufficient resolution, the pressure signals should be digitized to a resolution of 8-

12 bits at a sampling rate of at least 5-20 MHZ, but higher resolutions and sampling rates could be

used. The amplifier should have sufficient gain so that the analog thermal noise from the transducer

is greater than Vi LSB of the span of the analog-to-digital converter, or greater. Assuming the

amplifier/transducer circuit has an equivalent resistance of 50 Ohms, and the amplifier has a

bandwidth of approximately 4 MHZ, thermal noise will produce a signal magnitude of approximately 2 μvolts. Suitable resolution can be achieved by amplifying transducer signals with a 5 MHZ, 54 dB preamplifier available from Panametrics, and digitizing the amplified signals with an 8-bit, 20 MHZ

sampling rate analog-to-digital converter with a ±0.2 volt input span, manufactured by Gage

Electronics. Additionally, adjustable high pass filtering at 0.03, 0.1 and 0.3 can be added as needed

to achieve desired signal to noise performance.

As an example, Fig. 3 illustrates the pressure signals ?,(/) that might be produced by

four hypothetical transducers in response to pressure waves produced by a short duration of

electromagnetic irradiation of tissue. Fig. 3 shows the signal E(t) produced by computer circuit 36

(Fig. 1) on control line 38, which has a brief pulse, which causes microwave generator 22 to produce

a corresponding pulse of microwave energy. The resulting acoustic signals produced within breast 12 are subsequently received by each of the transducers, producing signals p t) having differing relative magnitudes and timing, as illustrated.

It is important that the transducers be small enough so that they are sensitive to sonic waves that impinge upon the transducers from a wide angle. Referring to Fig. 4, three hypothetical

absorbing regions 28a, 28b and 28c are shown in greater detail, along with the respectively

corresponding wavefronts 26a, 26b and 26c emitted by these regions, toward a transducer 33. Upon

irradiation, each region 28 is the origin of an acoustic pressure wave that travels in all directions. Part of each wave reaches transducer 33 after a delay time.

Transducer 33 is a piezoelectric ceramic chip (or a suitable alternative) having a

cross-sectional diameter d exposed to regions 28a, 28b and 28c. Electrical contacts (not shown) attached to the exterior of transducer 33 detect an electrical waveform produced by the chip in

response to mechanical vibration, as a result of the piezoelectric property of the ceramic chip.

Because the acoustic energy is transmitted in a wave, transducer 33 is not equally sensitive to the pressure waves from the three absorptive regions. The transducer is most sensitive to acoustic waves from region 28c, which lies on axis 40 of transducer 33 (axis 40 being defined by the

direction that lies at a 90° angle to the front surface of transducer 33). Transducer 33 is less sensitive

to acoustic waves from region 28b because this region is off of axis 40. Past a certain maximum

angle, θ, away from axis 40, transducer 33 is substantially insensitive to pressure waves such as

those from region 28a.

Maximum angle θ is given approximately by the relationship sin(θ) « vsτ/d, where vs

is the velocity of sound in the relevant medium (here, tissue), τ is the irradiation pulse length and d is the diameter of the transducer. Ifa relatively large volume is to be imaged, then θ should be as large

as possible (small d), but if dis too small, the transducer will produce a signal too weak to be electrically detectable without excessive noise. In general, the transducer diameter should be in the

range of vsτ < d< 4vsτ. The velocity of sound in tissue is approximately 1.5 mm/μs. Thus, for a nominal pulse width, τ, of 1 μs, d should be in the range of approximately 1.5 to 6.0 millimeters.

Fig. 5 illustrates a second embodiment of the invention identical in structure to Fig. 1 with the exception that a pulsed source 44 of visible or infrared radiation 46 is used to irradiate the

breast 12 instead of a microwave antenna. Also, a coupling media may not be needed due to the

close ml.064 μm, pulse width<10 nsec, 250 mJ/pulse), positioned approximately 50 mm from the

regions in the tissue to be imaged and collimated to a 25-100 mm diameter beam. Alternatively, radiation source 44 may be a flashtube energized by a pulsing power supply, such as a xenon

flashtube and power supply from Xenon Corp., Woburn, MA, which can produce a radiation pulse

with a 1 μsec rise time, followed by a decaying tail with a 4 μsec time constant. A cylindrically

curved, reflective surface (e.g., from Aluminum foil) may be used with the flash tube to direct radiation from the flash tube into the breast 12.

As noted above, array 32 is preferably of a sufficient size to image a substantial area of tissue. In some applications, however, the tissue to be imaged may be larger than array 32.

Referring to Fig. 6, in such situations, array 32 and the radiation source (antenna 22 or laser or

flashlamp 44) may be synchronously scanned in a rectilinear fashion as indicated by arrows 46 and

48. At each respective position of the radiation source and array 32, photoacoustic data is collected

and used to develop a corresponding image. The images may then be combined or superimposed to

produce a complete image of the breast 12. In this embodiment, scanning the transducer array

produces the effect of increasing the transducer array size, and increases the angular sampling of the

breast by the transducer array. Referring to Fig. 7, in another alternative embodiment of the present invention, the

transducer array 32 is rotated during the data acquisition, as indicated by arrow 50. Here again, the breast 12 is irradiated by microwave, visible or infrared radiation from an antenna 22, or laser or

flash tube 44. At each angular position of the transducer array, photoacoustic data is collected by the

transducers and used to develop a corresponding image. The images may then be combined or

superimposed to produce a complete image of the breast 12. In this embodiment, rotating the array 32 has the effect of increasing the effective number of transducer elements.

Fig. 8 illustrates a specific embodiment of a rotating spherically curved surface 52.

The radius of curvature of the surface 52 is R and the diameter of the array is D.

The position of each of the transducers in the spiral array, relative to the center C of curvature of surface 52, can be detailed with reference to Fig. 8. The position of each transducer 33 is given by three spherical coordinates (r,θ,φ) as is illustrated in Fig. 8. Each of the N transducers 33 is on the spherical surface (at a radius R), located at a unique (θ,φ), and is oriented on the surface

with its axis 40 (see Fig. 4) passing through the center C of the radius of curvature of the spherically curved surface 52. The φ positions of the transducers 33 range from a minimum angle of φm;„ to a

maximum angle of φmax. It is desirable to maximize this range of angles, i.e., so that φm∞mm is as large as possible, since doing so will enhance the extent to which features in the imaged tissue can be

reconstructed in multiple dimensions. (In some embodiments, φmaxmm typically must be less than

45°; however, in the embodiment of Fig. 13, φmαϊm,„ approaches 90°.)

The spiral array will be rotationally stepped to each of M positions during data acquisition, uniformly spanning 0<θ<360°. The (θ,φ) positions of each of the N transducers are

chosen so that after scanning, the locus of NxM transducer locations produced by the M rotational steps are distributed approximately uniformly over the spherical surface. To accomplish uniform distribution of transducer locations over the spherical surface

of the array, the θ-positions of the transducers are given as θ, = /'•(360/N)»( +(sinθmm/sinθmax)), where θ, is the θ-position of the i-th transducer (1 ≤z'≤N), and k is an arbitrary integer. The φ-

positions of the transducers are given recursively as φ,+ =φ,+(α/sin(φ,), where α is a constant that

depends on the radius of curvature of the spherical array and the diameter of the transducer, and

ΦrΦ m-

Two features of the rotationally scanned, spherical-spiral array are illustrated in Figs.

9 and 10. Fig. 9 illustrates the convergence of the axes 40 of the N transducers 33 to a single point within the breast. The convergence insures that the regions to which each of the N transducers is

most sensitive (see Fig. 4) will have a high degree of overlap, in an area 54 centered within the tissue under study. Also evident is the wide range of angles φ spanned by the transducer array.

Fig. 10 illustrates the nearly uniform distribution of the locus of transducer locations produced by rotation of a spherically curved surface 52 containing an array of N=32 transducers arranged in a spiral, when stepped to 32 evenly spaced angles of rotation θ in accordance with the foregoing. Referring to Fig. 10, one position of the 32 transducer elements is shown in cross-

hatching. The remaining 31 positions of the transducers arrived at by θ rotation of surface 52, are

illustrated in outline. As is apparent from Fig. 10, a nearly uniform distribution of the transducer

locations across the spherical surface is achieved.

Figs. 11 A and 1 IB illustrate a more specific embodiment of the invention,

incorporating a spherically curved spiral transducer array. Tank 16 containing acoustic media is

shaped to allow the tank to be brought alongside the body 56 of a patient to be examined. The breast 12 of the patient is compressed against the flexible sheet 30 to facilitate acoustic imaging. A source of radiation, either microwave, visible or infrared, is placed in contact with the opposite side of the breast 12 to stimulate photoacoustic waves from the breast tissue. Transducers 33 are mounted on a

spherically curved surface 52 such that their axes are directed toward the center of the radius of curvature of the surface 52, resulting in a large region of sensitivity overlap as previously illustrated in Fig. 9.

The spherical array 52 is rotated by a stepper motor on a support shaft 50 which is

journalled within tank 16. A suitable stepper motor controller (PC board) can be obtained from New

England Affiliated Technologies. The transducer array may be formulated from a monolithic, annular

array of five mm diameter elements, arranged in a spiral pattern as discussed above. Satisfactory results have been achieved using low-Q ceramic transducers having a wide band frequency response

from 200 kHz to 2 MHZ, falling to zero near 4 MHZ.

The annular array is encased in an aluminum-shielded housing in which preamplifiers and line drivers are incorporated. Referring to Fig. 12, a suitable amplifier circuit can be constructed from a JFET 57 and bipolar transistor 59 arranged in a dual-stage amplifier. Signals output from the integral amplifier/line drivers are led outside of tank 16 using ultra-thin coaxial cable cables, to an

external amplifier and analog-to-digital converter.

Fig. 13 illustrates another embodiment of the invention, specifically adapted for

human breast imaging, in which the angle φm∞m,„ of spherically curved surface 52 is substantially larger than in the preceding embodiment. In this embodiment, the microwave source is a helical,

"end-launch" antenna 20, for which the spherically curved, conductive surface of the spherical

transducer array 52 serves as a ground plane. Surface 52 also serves as a tank for containing an acoustic and electromagnetic coupling media 18/29. (Distilled and deionized water serves as a

suitable acoustic/electromagnetic coupling media.) The breast is suspended vertically into the coupling media 18/29 as illustrated, to permit coupling of both microwave energy into the breast and acoustic energy out of the breast. The individual transducers 33 are arranged as a spherical, spiral array as previously described, and the surface 52 is rotated on shaft 50 to collect an even distribution

of samples from the transducers.

After sonic pressure waves are recorded using one of the embodiments of the

invention described above, photoacoustic images must be "reconstructed" from multiple pressure signals. The aim is to reconstruct some property of the breast from an ensemble of pressure

measurements made externally to the breast. In this case, these measurements are time-dependent

pressure signals recorded subsequent to object-irradiation by a short pulse of radiation.

The generalized reconstruction geometry is illustrated in Fig. 14. The excess pressure p(r,i) that arrives at position r, where transducer 33 is located, at time t, is the sum of the pressure

waves produced at all positions within the tissue. This sum can be expressed as a volume integral:

dr' d2 T (r', t ' p(r't) aJ 4 -/J7 - r~-r - - " d"f: - ' (1) where p is the mass density and β is the coefficient of thermal expansion of the tissue, the volume

integral is carried out over the entire r'-space where the temperature acceleration d2T(r',t')/dt'2 is

non-zero, and where t-t-|r-r'|/v8 (|r-r'|/vs being the time delay for an acoustic pressure wave to

propagate from position r' to position r at the speed of sound in tissue vs).

Under the assumption that the radiation pulse which causes the temperature

acceleration is of a duration τ which is short enough (τ<l μs) to generate an adiabatic expansion of absorptive tissue, the preceding equation can be rewritten in terms of a regional heat absorption

function S(r',t):

(r, t) - AJπ-C/J/J/J 3S' d';t ' ,) r-r',', <2> where C is the specific heat of tissue. We can further write the heating-function as the product of a purely spatial and a purely temporal component, i.e.,

S ( r', t /) =I0R (r') T ( t /) (3 ) where I0 is a scaling factor proportional to the incident radiation intensity and R(r') represents the

fractional energy absorption of r'. Defined in this way IoT(/') describes the irradiating field and R(r')

describes the absorption properties of the medium (breast). The excess pressure can then be written as:

Equation 4 expresses how the time-sequential information conveyed by the pressure signal delivers spatial information about the absorption properties of the medium.

To further simplify, both sides of equation (4) are integrated in time and multiplying factors are moved to the left, to obtain:

Now, assuming that the temporal distribution of the irradiating field is of unit height

and duration τ (see the function E(t) illustrated in Fig. 3), T(t') has a value of 1 only from t-0 to

t-τ. As a result, the integrand on the right side of equation (5) will have a value of zero everywhere

except along a thin, spherical "shell" of inner radius vst surrounding point r, where 0<t'<τ, i.e., where

|r-r'|/vs < t < τ + |r-r'|/vs. This thin "shell" has a thickness of vsτ; accordingly, the volume integral for

this thin "shell" can be approximated by vsτ multiplied by the surface integral, over the inner surface

of the "shell", i.e., where |r-r'|/v, = t, i.e.:

Finally, noting that |r-r'| = vst, and rearranging terms, we can define the "projection" at the

position r, Sr(t), as

R (r') dr' (7 )

Equation (7) shows that the integral of all pressure waves received at a transducer at

position r and up to time t, is proportional to the sum of the absorption function over a spherical

surface a distance vst from the transducer. Accordingly, an image of R(r') can be reconstructed by

mapping integrated pressure data acquired at multiple transducers, over spherical surfaces (to create three-dimensional image) or co-planar arcs (to create a two-dimensional image).

Specifically, referring to Fig. 15, this method of image reconstruction comprises:

1. Positioning transducers acoustically coupled to the tissue under study (step

60).

2. Positioning an electromagnetic source electromagnetically coupled to the tissue under study (step 62).

3. Irradiating the tissue with a brief pulse of electromagnetic energy E(t) at time

t=0 to induce acoustic signals in the tissue (step 64).

4. Sampling and storing pressure measurements Pt(t) at each transducer i beginning at time t-0 (step 66).

t

5. Computing the sums s , { t) = t p . ( t ') of pressure signals (step 68). t '=0 6. For a point r' in the tissue to be imaged, determining the time delay tj needed

for sound to travel from point r' to the position of transducer i (step 70), selecting the value of the

sum Si(tj) (generated from transducer i) which occurs at time t; (step 72), repeating these steps for

each transducer i (step 74), and then accumulating the selected values S^t;) to generate a value K(r')

N I z-. -r'l at position r' according to K ( r') = A∑ Si ( — ) (8) (step 76).

_ ι 2 v\

8. Repeating step 7 for each point r' to be imaged (step 78).

9. Spatially filtering the resulting values of K(r') to obtain values for R(r'). This

filtering can be performed in the frequency domain using a function having a response proportional to the square of frequency. Alternatively, filtering may be performed by computing the Laplacian of

the three-dimensional spatial function K(r'), i.e., R(r')=A-V2K(r') (9) (Step 70).

9. Plotting the values of R(r') as an image of the tissue (step 82).

This reconstruction methodology was generally tested for a two-dimensional image, by constructing the simplified experimental test bed illustrated in Fig. 16. The test bed included a

wideband transducer 82 with a center frequency of 2 MHZ, mounted on a 150 mm arm that was

rotated along a circular path 84 under stepper-motor control. The transducer was 50 mm (height) X

6 mm (width) and had a radius of curvature of 150 mm along the long dimension. The transducer

was asymmetrical and focused in one dimension radially inwardly with respect to path 84;

accordingly, the transducer was most responsive to acoustic signals received over a wide angle

within the horizontal plane of circular path 84.

The scanning mechanism was immersed in a 50 ml/1 concentration Intralipid-10%, a

fatty emulsion frequently used as a tissue-mimicking scattering medium. The scattering coefficient (μs) for Intralipid-10% @ 1.064 μm was measured as 0.015 mm'Vml/l. This is close to the 0.013 mm"Vml/l reported by van Staveren. (See van Staveren, H.J., et al., "Light scattering in Intralipid-

10% in the wavelength range of 400-1100 nm", Applied Optics. 31(1):4507-4514 (1991).) Using a

value of 0.48 for the mean cosine of scatter (g), as reported by van Staveren, and the scattering

coefficient measured in our laboratory, the 50 ml/1 concentration of Intralipid-10% produced a

reduced scattered coefficient μs' = 0.39 mm"1s' ≡ (1 - g ) μ . At this wavelength, the absorption of

Intralipid-10% is due almost entirely to the absorption of water, μa ≡ 0.0164 mm"19. These values are a factor of 2-3 less than those measured in vitro for different types of breast tissue at 900 nm.

A 50 mm diam laser beam from a pulsed Nd: YAG laser (λ=l .064 μm, pulse

width<10 ns, 20 Hz repetition rate, 250 mJ/pulse) illuminated the scattering medium from below. The imaging plane of path 84 was normal to the laser beam and was located 47.5 mm above the

bottom surface of the scattering medium. The laser beam axis and rotational axis of the transducer

scanning arm were coincident.

Data acquisition proceeded as follows: The transducer was stepped through 360° at

2° increments along path 84. At each angle, the temporal acoustic signal recorded by the transducer

was digitized to 12 bits at a rate of 10 MHZ for a total of 1024 samples. The sampling interval was synchronized to the pulsing of the laser. At each angle, the temporal acoustic signal for 16

consecutive pulses were averaged. This procedure was repeated for 180 angles.

The absorption phantom illustrated in Fig. 16 was used in imaging. It consisted of a 4

mm diam, black, latex ball 86 and a black, rubber cylinder 88 suspended on two, 0.35 mm diam,

clear, polyethylene threads. The dimensions for the cylinder were 8.5 mm outside diameter 5.0 mm inside diameter and 4 mm length. Image reconstruction proceeded using an adaptation of the integrated, filtered-back

projection algorithm described above, applicable to a two-dimensional image. The Sr(t) were

computed for each of the 180 transducer angles, backprojected over appropriate arcs and summed.

A value of v, = 1.5 mm/μs was assumed. The next step was to apply a 2-D filter. Filtering was

performed in the frequency domain using a linear ramp function a cosine-weighted apodizing window, i.e., Fφ=\f/fπ\*(l+cos(πf/fn))/2, where/is the spatial frequency and/„ is the Nyquist

frequency associated with the reconstruction matrix. In this instance, , = 3 cycles/mm. The center

30mm region of the reconstruction is displayed in Fig. 17.

The basic relationship between an acoustic signal and a heterogeneous distribution of absorbed energy is given by Equation 7. At any moment in time following an irradiating optical pulse, the temporally weighted and temporally integrated acoustic pressure up to that time is

proportional to a surface integral of the absorbed heat distribution R(r) within the object being

imaged. This relationship is true, provided the irradiating optical pulse is short enough and sharp

enough. This condition is met for optical pulses less than 1 μs duration.

In order to "reconstruct" R(r') from a set of acoustic measurements, data must be

sampled over at least 2π steradians. In the restricted case, where significant optical absorption takes

place within a narrow plane, R(r') can be reconstructed using a set of co-planar acoustic data

acquired over 360°. The image displayed in Fig. 17 was reconstructed under these conditions. This image reflects what one would expect: a "cut" through the center of a spherical and cylindrical absorber. It is of note that a "halo" artifact surrounds the image of the latex ball 86. This originates from the decreased velocity of sound within the latex ball (1.0 mm/μs) compared to the Liposyn-

10% solution (1.5 mm/μs). Were R(r') distributed throughout a larger volume, it would have been necessary to

obtain acoustic data over the surface of a hemisphere in order to adequately reconstruct R(r'). Such

an operation can be performed by the transducer geometries described above.

Further details on the above experimental arrangement can be found in Kruger et al.,

"Photoacoustic ultrasound (PAUS) — Reconstruction tomography", Medical Physics 22(10): 1605-

1609 (October 1995), incorporated by reference herein in its entirety.

A second methodology for image generation can also be derived from Equations (8)

and (9). Specifically, it can be shown that the Laplacian of the back-projection of the time- weighted, integrated pressure signals is approximately equal to the back-projection of the first time derivative

of the pressure signal, if the radius R of any imaged object is small, i.e., where |r-r' |»R, as follows:

R {r') =A∑ t . x (10) i =X dt

where t{ = | r,-r' |/vg, r' is a vector that denotes the location within the tissue, η is a vector that denotes

the location of transducer i, vs is the velocity of sound, A is a constant, and p,(t) is the samples of the pressure signal that reaches the i-th transducer.

Referring to Fig. 18, using this approximation, the steps in the reconstruction process are as follows:

1. Positioning transducers acoustically coupled to the tissue under study (step 114).

2. Positioning an electromagnetic source electromagnetically coupled to the tissue

under study (step 116).

3. Irradiating the tissue with brief pulse of electromagnetic energy E(t) at time t=0 to induce acoustic signals in tissue (step 118). 4. Sampling and storing pressure measurements pA(t) at each transducer beginning at

time t=0 (step 120).

5. Calculating the time- weighted, first temporal derivative ofp tj, i.e., t^dp tj/dt), for each of the / transducers (step 122).

6. For each position, r', in the tissue, summing the selected values of the time-

weighted first temporal derivatives of the pressure signals from each transducer as indicated in Equation 9 (steps 124 - 132).

7. Generating an image of the tissue from computed values of R(r') (step 134).

This reconstruction procedure produces three-dimensional images of the energy deposition within the interior of the tissue, which is representative of the differential absorption of the irradiating energy by the different types of tissues within the tissue.

To perform the above calculation, it is necessary to obtain the first time-derivative of

the pressure signal that reaches each transducer. It should be noted, however, that a transducer

produces a characteristic "ringing" in its electrical response to an externally-applied pulse of pressure, which distorts the shape of the electrical output of the transducer away from that of the

pressure waveform. Referring to Fig. 19, this ringing response 136 approximates the impulse

response of the transducer 33, i.e., the electrical signal as a function of time that is produced when a

very abrupt pressure impulse 138 strikes the transducer.

If a transducer were fabricated to produce a simple biphasic (or "doublet") response to an impulse of pressure, that is one positive lobe, followed a short time later by one negative lobe (an ideal response 136 is illustrated in Fig. 19), then the electrical output of the transducer would be

approximately proportional to the first time-derivative of the input pressure signal. This would be desirable, because it would eliminate the necessity of computing the first time-derivative of the input

pressure signal; rather, the time derivative would be produced by the transducer in the first instance.

For any real transducer, however, such a response would be difficult to achieve.

Rather, the impulse response of a transducer is closer to a damped sinusoid, as is illustrated in

waveform 140 p(t)) in Fig. 20. In this example, the impulse response of the transducer is assumed to

be of the ϊormp(t) = sin(2π/t)eαft. Such a response displays a periodic component of a characteristic

temporal frequency/, that decays exponentially with time.

In this case, an approximate "differential" transducer response can by synthesized by delaying the originally recorded pressure waveform, p(t), by varying amounts, weighing the delayed pressure signals, and summing the delayed pressure signals together with the original waveform. An

example is illustrated in Fig. 20, which shows two weighted, time-delayed waveforms (Ap(t-Δt) 142

and Bp(t-2Δt) 144 (where Δt is l/2f) generated from the assumed impulse response 140 of the transducer. When the time-delayed waveforms 142 and 144 are added to the response 140 of the

transducer, the resulting waveform 146 synthesizes a biphasic impulse response S(t).

Thus, to implement the reconstruction algorithm described above, the transducer

responses can be synthesized to be differential in nature using the methodology illustrated in Fig. 20, after which the output of each transducer will be proportional to dp(t)/dt.

Referring to Fig. 21, a circuit for performing such a reconstruction includes an analog-to-digital converter 148 for converting the analog signal from the transducer to an equivalent

digital signal, an amplifier 149 and cache 150 for receiving and temporarily storing samples from A/D converter 148 and outputting the sample which was stored Δt earlier multiplied by a gain factor

A, a second amplifier 151 and cache 152 for storing samples and outputting the sample which was stored 2Δt earlier multiplied by a gain factor B, and a digital accumulator 154 for summing the outputs of caches 148 and 150 with the current sample from the A/D converter to produce an output digital signal S which is representative of dp(t)/dt.

Using a circuit such as that shown in Fig. 21, steps 120 and 122 of the reconstruction

process described by Fig. 18 can be accomplished in a single operation by hardware rather than in

software computations, increasing the scanning and imaging rate of the apparatus.

While the present invention has been illustrated by a description of various

embodiments and while these embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such

detail. Additional advantages and modifications will readily appear to those skilled in the art. The

invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method, and illustrative example shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant's general inventive

concept.

What is claimed is:

Claims

1. A method of imaging tissue structures in a three-dimensional volume of tissue by detecting localized absorption of electromagnetic waves in said tissue, comprising providing a source of electromagnetic radiation in proximity to said tissue; providing a plurality of acoustic sensors; acoustically coupling said plurality of acoustic sensors to said tissue; irradiating said three-dimensional volume of tissue with a pulse of electromagnetic radiation from said source to generate resultant pressure waveforms within said three-dimensional volume of tissue; detecting said resultant pressure waveforms arriving at said acoustic sensors and storing data representative of said waveforms; combining a plurality of detected pressure waveforms to derive a measure of pressure waveforms originating at a point by: determining a distance between said point and a pressure sensor, computing a value related to the time rate of change in a pressure waveform detected by said pressure sensor, at a time which is a time delay after said pulse of electromagnetic radiation, said time delay being equal to the time needed for sound to travel said distance through said tissue; repeating said determining and computing for additional pressure sensors and pressure sensor waveforms, and accumulating said computed values to form said measure of pressure waveforms originating at said point; and repeating said combining step for a plurality of points to produce an image of structures in said tissue.
2. The method of claim 1 wherein said step of providing a plurality of acoustic sensors comprises providing a differentiating acoustic sensor responsive to a pressure waveform by producing an electrical output representative of a time rate of change of said pressure waveform, and said step of computing a value of the time rate of change in a pressure waveform, comprises computing a value of said electrical output of said differentiating pressure sensor.
3. The method of claim 2 wherein said differentiating acoustic sensor includes a piezoelectric crystal which produces an analog signal, and producing an electrical output representative of a time rate of change comprises combining a delayed version of said analog signal with said analog signal to produce said electrical output.
4. The method of claim 1 wherein computing a value related to the time rate of change in a pressure waveform at a time delay, further comprises multiplying said time rate of change by a factor proportional to said time delay to produce said value, whereby to compensate for diffusion of acoustic energy radiated from said point.
5. The method of claim 1 wherein providing said plurality of sensors comprises providing a surface and positioning said sensors evenly spaced across said surface.
6. The method of claim 5 wherein said steps of irradiating said tissue and detecting said pressure waveforms are performed while said surface and said sensors are at a first position, and further comprising the steps of moving said surface and said sensors to a second position, repeating said irradiating step, repeating said detecting step, and combining waveforms collected by said sensors in said first and said second positions to generate said image of said tissue.
7. The method of claim 6 wherein moving said surface comprises moving said surface in a rectilinear fashion.
8. The method of claim 6 further comprising moving said electromagnetic radiation source in synchrony with said surface and said sensors.
9. The method of claim 6 wherein moving said surface comprises rotating said surface.
10. The method of claim 9 wherein said sensors are positioned on said surface along a spiral path.
11. The method of claim 1 further comprising immersing said sensors in an acoustic coupling media, said acoustic coupling media having an acoustic characteristic impedance which is substantially similar to that of said tissue to reduce reflections of acoustic waves impinging into said media from said tissue.
12. The method of claim 11 further comprising providing a flexible film containing said acoustic coupling media, and pressing said tissue upon said flexible film to couple acoustic waves from said tissue into said acoustic coupling media.
13. The method of claim 1 further comprising immersing said electromagnetic radiation source in an electromagnetic coupling media, said electromagnetic coupling media having an electromagnetic characteristic impedance which is substantially similar to that of said tissue to reduce reflections of electromagnetic waves impinging into said tissue from said electromagnetic coupling media.
14. The method of claim 13 further comprising providing a flexible film enclosing electromagnetic coupling media, and pressing said tissue upon said flexible film to couple electromagnetic waves from said electromagnetic coupling media into said tissue.
15. The method of claim 11 further comprising immersing said electromagnetic radiation source in said acoustic coupling media, wherein said acoustic coupling media has a characteristic electromagnetic impedance which is substantially similar to that of said tissue, to reduce reflections of electromagnetic waves impinging into said tissue from said media.
16. The method of claim 1 wherein irradiating said tissue comprises irradiating said tissue with a laser generating electromagnetic radiation in the near-infrared band.
17. The method of claim 1 wherein irradiating said tissue comprises irradiating said tissue with a Xenon flash lamp.
18. The method of claim 1 wherein irradiating said tissue comprises irradiating said tissue with an electrically conductive coil generating microwave frequency radiation.
19. The method of claim 18 wherein said microwave frequency is substantially four hundred and thirty-three MHZ.
20. The method of claim 18 wherein said microwave frequency is substantially nine hundred and fifteen MHZ.
21. A method of imaging tissue structures by detecting localized absorption of electromagnetic waves in said tissue, comprising providing a source of electromagnetic radiation in proximity to said tissue; providing a surface and positioning a plurality of acoustic sensors spaced across said surface; acoustically coupling said plurality of acoustic sensors to said tissue; positioning said surface and said sensors in a first position; irradiating said tissue with a pulse of electromagnetic radiation from said source to generate resultant pressure waveforms within said tissue; detecting said resultant pressure waveforms arriving at said acoustic sensors and storing data representative of said waveforms; moving said surface and said sensors to a second position; repeating said irradiating step; repeating said detecting step; combining a plurality of said detected pressure waveforms collected by said sensors in said first and said second positions to derive a measure of pressure waveforms originating at a point distant from said acoustic sensors; and repeating said combining step for a plurality of points to produce an image of structures in said tissue.
22. The method of claim 21 wherein moving said surface and said sensors to a second position comprises rotating said surface and said sensors.
23. The method of claim 22 wherein said sensors are arranged on said surface along a spiral path.
24. A method of imaging tissue structures by detecting localized absorption of electromagnetic waves in said tissue, comprising providing a coupling media adjacent said tissue; providing a flexible film enclosing said coupling media; providing a source of electromagnetic radiation in proximity to said tissue; providing a plurality of acoustic sensors in proximity to said tissue; at least one of said source of electromagnetic radiation and said sensors being immersed in said coupling media; pressing said tissue upon said flexible film to couple said tissue to said coupling media; irradiating said tissue with a pulse of electromagnetic radiation from said source to generate resultant pressure waveforms within said tissue; detecting said resultant pressure waveforms arriving at said acoustic sensors and storing data representative of said waveforms; combining a plurality of said detected pressure waveforms to derive a measure of pressure waveforms originating at a point distant from said acoustic sensors; and repeating said combining step for a plurality of points to produce an image of structures in said tissue.
25. A method of imaging tissue structures by detecting localized absorption of electromagnetic waves in said tissue, comprising providing an acoustic coupling media adjacent said tissue, having an acoustic characteristic impedance which is substantially similar to that of said tissue to reduce reflections of acoustic waves impinging into said media from said tissue; providing a plurality of acoustic sensors and immersing said sensors in said acoustic coupling media to acoustically couple said plurality of acoustic sensors to said tissue; providing an electromagnetic coupling media adjacent said tissue, said electromagnetic coupling media having an electromagnetic characteristic impedance which is substantially similar to that of said tissue to reduce reflections of electromagnetic waves impinging into said tissue from said electromagnetic coupling media; providing a source of electromagnetic radiation in proximity to said tissue and immersing said source in said electromagnetic coupling media to electromagnetically couple said source to said tissue; irradiating said tissue with a pulse of electromagnetic radiation from said source to generate resultant pressure waveforms within said tissue; detecting said resultant pressure waveforms arriving at said acoustic sensors and storing data representative of said waveforms; combining a plurality of said detected pressure waveforms to derive a measure of pressure waveforms originating at a point distant from said acoustic sensors; and repeating said combining step for a plurality of points to produce an image of structures in said tissue.
26. Apparatus for imaging tissue structures in a three-dimensional volume of tissue by detecting localized absorption of electromagnetic waves in said tissue, comprising an electromagnetic radiation source; a plurality of acoustic sensors arrayed across a surface, said surface being acoustically coupled to said tissue; power circuitry pulsing said electromagnetic radiation source to produce a pulse of electromagnetic radiation from said source irradiating said three-dimensional volume of tissue to generate resultant pressure waveforms within said three-dimensional volume of tissue; and computing circuitry detecting resultant pressure waveforms arriving at said acoustic sensors, storing data representative of said waveforms, and combining a plurality of detected pressure waveforms to derive a measure of pressure waveforms originating at each of a number of points to form an image, by determining for each point a distance between said point and a pressure sensor, computing a value related to the time rate of change in a pressure waveform detected by said pressure sensor, at a time which is a time delay after said pulse of electromagnetic radiation, said time delay being equal to the time needed for sound to travel said distance through said tissue, repeating said determining and computing for additional pressure sensors and pressure sensor waveforms, and accumulating said computed values to form said measure of pressure waveforms originating at said point.
27. The apparatus of claim 26 wherein said sensors are piezoelectric transducers having a largest dimension smaller than four times the distance traveled by sound in tissue over the time duration of said pulse of electromagnetic radiation.
28. The apparatus of claim 26 wherein said sensors are evenly spaced across said surface.
29. The apparatus of claim 26 further comprising a motor coupled to said surface for moving said surface and said sensors to generate said image of said tissue.
30. The apparatus of claim 29 wherein said motor moves said surface in a rectilinear fashion.
31. The apparatus of claim 30 further comprising a second motor coupled to said electromagnetic radiation source for moving said source in synchrony with said surface and said sensors.
32. The apparatus of claim 29 wherein said motor rotates said surface.
33. The apparatus of claim 32 wherein said sensors are positioned on said surface along a spiral path.
34. The apparatus of claim 26 further comprising a tank enclosing an acoustic coupling media, said surface and said sensors being immersed in said tank.
35. The apparatus of claim 34 wherein said tank includes an open top surface whereby said tissue may be received into said acoustic coupling media.
36. The apparatus of claim 34 wherein said tank further comprises a flexible film cover enclosing said tank to contain said acoustic coupling media, whereby said tissue may be pressed upon said flexible film to couple acoustic waves from said acoustic coupling media into said tissue.
37. The apparatus of claim 34 further comprising a second tank enclosing an acoustic coupling media.
38. The apparatus of claim 37 wherein said second tank further comprises a flexible film cover enclosing said tank to contain said electromagnetic coupling media, whereby said tissue may be pressed upon said flexible film to couple electromagnetic waves from said electromagnetic coupling media into said tissue.
39. The apparatus of claim 34 wherein said electromagnetic radiation source is positioned inside of said tank and immersed in said acoustic coupling media, whereby said acoustic coupling media in said tank may be selected to have a characteristic electromagnetic impedance which is substantially similar to that of said tissue, to reduce reflections of electromagnetic waves impinging into said tissue from said media.
40. The apparatus of claim 26 wherein said electromagnetic radiation source is a laser.
41. The apparatus of claim 40 wherein said laser emits electromagnetic radiation in the near- infrared band.
42. The apparatus of claim 40 wherein said laser is a Nd:YAG laser.
43. The apparatus of claim 26 wherein said electromagnetic radiation source is a flash lamp.
44. The apparatus of claim 43 wherein said flash lamp is a Xenon flash lamp.
45. The apparatus of claim 26 wherein said electromagnetic radiation source is an electrically conductive coil.
46. The apparatus of claim 45 wherein said power circuitry pulses said coil at a microwave frequency.
47. The apparatus of claim 46 wherein said microwave frequency is substantially four hundred and thirty-three MHZ.
48. The apparatus of claim 46 wherein said microwave frequency is substantially nine hundred and fifteen MHZ.
49. Apparatus for imaging tissue structures by detecting localized absorption of electromagnetic waves in said tissue, comprising an electromagnetic radiation source; a plurality of acoustic sensors arrayed across a surface, said surface being acoustically coupled to said tissue; a motor coupled to said surface for moving said surface and said sensors; power circuitry pulsing said electromagnetic radiation source to produce a pulse of electromagnetic radiation from said source within said tissue; and computing circuitry detecting resultant pressure waveforms arriving at said acoustic sensors when said sensors are in multiple different positions, storing data representative of said waveforms, and combining a plurality of said detected pressure waveforms to derive an image, points in said image being derived by combining measures of pressure waveforms originating at points within said tissue.
50. The apparatus of claim 49 wherein said motor moves said surface by rotating said surface.
51. The apparatus of claim 50 wherein said sensors are arrayed across said surface along a spiral path.
52. Apparatus for imaging tissue structures in a three-dimensional volume of tissue by detecting localized absorption of electromagnetic waves in said tissue, comprising an electromagnetic radiation source; a plurality of acoustic sensors arrayed across a surface, said surface being acoustically coupled to said tissue; power circuitry pulsing said electromagnetic radiation source to produce a pulse of electromagnetic radiation from said source irradiating said three-dimensional volume of tissue to generate resultant pressure waveforms within said three-dimensional volume of tissue; a tank containing a coupling media, at least one of said electromagnetic radiation source and said surface being immersed in said coupling media in said tank; a flexible film cover enclosing said tank to contain said coupling media, whereby said tissue may be pressed upon said flexible film to couple to said coupling media; and computing circuitry detecting resultant pressure waveforms arriving at said acoustic sensors, storing data representative of said waveforms, and combining a plurality of said detected pressure waveforms to derive an image, points in said image being derived by combimng measures of pressure waveforms originating at points within said tissue.
53. Apparatus for imaging tissue structures by detecting localized absorption of electromagnetic waves in said tissue, comprising a first tank containing an acoustic coupling media having an acoustic characteristic impedance which is substantially similar to that of said tissue to reduce reflections of acoustic waves impinging into said media from said tissue; a second tank containing an electromagnetic coupling media having an electromagnetic characteristic impedance which is substantially similar to that of said tissue to reduce reflections of electromagnetic waves impinging into said tissue from said electromagnetic coupling media; a plurality of acoustic sensors positioned within said first tank and immersed in said acoustic coupling media; an electromagnetic radiation source positioned within said second tank and immersed in said electromagnetic coupling media; power circuitry pulsing said electromagnetic radiation source to produce a pulse of electromagnetic radiation from said source within said tissue; and computing circuitry detecting resultant pressure waveforms arriving at said acoustic sensors, storing data representative of said waveforms, and combining a plurality of said detected pressure waveforms to derive an image, points in said image being derived by combining measures of pressure waveforms originating at points within said tissue.
54. The apparatus of claim 53 wherein at least one of said tanks further comprises a flexible film cover enclosing said tank to contain said coupling media, whereby said tissue may be pressed upon said flexible film to couple said tissue to said coupling media.
55. Apparatus for imaging tissue structures by detecting localized absorption of electromagnetic waves in said tissue, comprising a tank containing a coupling media having an acoustic characteristic impedance which is substantially similar to that of said tissue to reduce reflections of acoustic waves impinging into said media from said tissue, and having an electromagnetic characteristic impedance which is substantially similar to that of said tissue to reduce reflections of electromagnetic waves impinging into said tissue from said coupling media; an electromagnetic radiation source positioned inside of said tank and immersed in said coupling media; a plurality of acoustic sensors positioned within said tank and immersed in said coupling media; power circuitry pulsing said electromagnetic radiation source to produce a pulse of electromagnetic radiation from said source within said tissue; and computing circuitry detecting resultant pressure waveforms arriving at said acoustic sensors, storing data representative of said waveforms, and combining a plurality of said detected pressure waveforms to derive an image, points in said image being derived by combining measures of pressure waveforms originating at points within said tissue.
PCT/US1997/017832 1996-10-04 1997-10-01 Photoacoustic breast scanner WO1998014118A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US08/719,736 1996-10-04
US08719736 US5713356A (en) 1996-10-04 1996-10-04 Photoacoustic breast scanner

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
JP51688498A JP4341987B2 (en) 1996-10-04 1997-10-01 Photoacoustic chest scanner
DE1997638998 DE69738998D1 (en) 1996-10-04 1997-10-01 Photoacoustic mom scanning
EP19970944607 EP0942683B1 (en) 1996-10-04 1997-10-01 Photoacoustic breast scanner
US09076968 US6102857A (en) 1996-10-04 1998-05-13 Photoacoustic breast scanner
US09604752 US6292682B1 (en) 1996-10-04 2000-06-27 Photoacoustic breast scanner
US09954332 US20020035327A1 (en) 1996-10-04 2001-09-17 Photoacoustic breast scanner

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
US08719736 Continuation US5713356A (en) 1996-10-04 1996-10-04 Photoacoustic breast scanner

Related Child Applications (2)

Application Number Title Priority Date Filing Date
US09076968 Division US6102857A (en) 1996-10-04 1998-05-13 Photoacoustic breast scanner
US09604752 Division US6292682B1 (en) 1996-10-04 2000-06-27 Photoacoustic breast scanner

Publications (1)

Publication Number Publication Date
WO1998014118A1 true true WO1998014118A1 (en) 1998-04-09

Family

ID=24891163

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1997/017832 WO1998014118A1 (en) 1996-10-04 1997-10-01 Photoacoustic breast scanner

Country Status (6)

Country Link
US (4) US5713356A (en)
EP (1) EP0942683B1 (en)
JP (1) JP4341987B2 (en)
CA (1) CA2187701C (en)
DE (1) DE69738998D1 (en)
WO (1) WO1998014118A1 (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002015776A1 (en) 2000-08-24 2002-02-28 Glucon Inc. Photoacoustic assay and imaging system
US7646484B2 (en) 2002-10-07 2010-01-12 Intellidx, Inc. Method and apparatus for performing optical measurements of a material
US8332006B2 (en) 2004-05-06 2012-12-11 Nippon Telegraph And Telephone Corporation Constituent concentration measuring apparatus and constituent concentration measuring apparatus controlling method
US8814794B2 (en) 2009-12-17 2014-08-26 Canon Kabushiki Kaisha Measuring system, image forming method, and program
US8920321B2 (en) 2008-06-18 2014-12-30 Canon Kabushiki Kaisha Photoacoustic imaging apparatus
US9924876B2 (en) 2013-03-29 2018-03-27 Canon Kabushiki Kaisha Object information acquiring apparatus and method of controlling same

Families Citing this family (175)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6309352B1 (en) * 1996-01-31 2001-10-30 Board Of Regents, The University Of Texas System Real time optoacoustic monitoring of changes in tissue properties
US6405069B1 (en) 1996-01-31 2002-06-11 Board Of Regents, The University Of Texas System Time-resolved optoacoustic method and system for noninvasive monitoring of glucose
US5713356A (en) * 1996-10-04 1998-02-03 Optosonics, Inc. Photoacoustic breast scanner
US6132374A (en) * 1997-08-01 2000-10-17 Acuson Corporation Ultrasonic imaging method and system
US5924986A (en) * 1997-09-10 1999-07-20 Acuson Corporation Method and system for coherent ultrasound imaging of induced, distributed source, bulk acoustic emissions
US6104942A (en) * 1998-05-12 2000-08-15 Optosonics, Inc. Thermoacoustic tissue scanner
US5957852A (en) * 1998-06-02 1999-09-28 Acuson Corporation Ultrasonic harmonic imaging system and method
US6116244A (en) * 1998-06-02 2000-09-12 Acuson Corporation Ultrasonic system and method for three-dimensional imaging with opacity control
US6511426B1 (en) 1998-06-02 2003-01-28 Acuson Corporation Medical diagnostic ultrasound system and method for versatile processing
US6048316A (en) * 1998-10-16 2000-04-11 Acuson Corporation Medical diagnostic ultrasonic imaging system and method for displaying composite fundamental and harmonic images
EP1123504A2 (en) * 1998-10-19 2001-08-16 THE GOVERNMENT OF THE UNITED STATES OF AMERICA, as represented by THE SECRETARY OF THE DEPARTMENT OF HEALTH AND HUMAN SERVICES Electroacoustic imaging methods and apparatus
US6216025B1 (en) 1999-02-02 2001-04-10 Optosonics, Inc. Thermoacoustic computed tomography scanner
US6364849B1 (en) 1999-05-03 2002-04-02 Access Wellness And Physical Therapy Soft tissue diagnostic apparatus and method
US6264610B1 (en) * 1999-05-05 2001-07-24 The University Of Connecticut Combined ultrasound and near infrared diffused light imaging system
US6567688B1 (en) * 1999-08-19 2003-05-20 The Texas A&M University System Methods and apparatus for scanning electromagnetically-induced thermoacoustic tomography
US6212421B1 (en) * 1999-09-03 2001-04-03 Lockheed Martin Energy Research Corp. Method and apparatus of spectro-acoustically enhanced ultrasonic detection for diagnostics
US6694173B1 (en) * 1999-11-12 2004-02-17 Thomas Bende Non-contact photoacoustic spectroscopy for photoablation control
US6359367B1 (en) * 1999-12-06 2002-03-19 Acuson Corporation Micromachined ultrasonic spiral arrays for medical diagnostic imaging
US6503204B1 (en) * 2000-03-31 2003-01-07 Acuson Corporation Two-dimensional ultrasonic transducer array having transducer elements in a non-rectangular or hexagonal grid for medical diagnostic ultrasonic imaging and ultrasound imaging system using same
KR20030015389A (en) 2000-07-14 2003-02-20 록히드 마틴 코포레이션 A system and method of determining porosity in composite materials using ultrasound
WO2002008740A3 (en) 2000-07-23 2003-01-23 Israel Atomic Energy Comm Apparatus and method for probing light absorbing agents in biological tissues
US20050085725A1 (en) * 2001-08-09 2005-04-21 Ron Nagar Photoacoustic assay and imaging system
JP4781548B2 (en) * 2001-03-14 2011-09-28 浜松ホトニクス株式会社 Breast cancer detection device
US6490470B1 (en) * 2001-06-19 2002-12-03 Optosonics, Inc. Thermoacoustic tissue scanner
US7123752B2 (en) * 2001-12-19 2006-10-17 Sony Corporation Personal identification apparatus and method
US20030124712A1 (en) * 2002-01-02 2003-07-03 Bauman Mark A. Method and apparatus for differentiating articles in a product stream
US7091879B2 (en) * 2002-02-05 2006-08-15 Invivo Corporation System and method for using multiple medical monitors
KR100416764B1 (en) * 2002-03-21 2004-01-31 삼성전자주식회사 Non-invasive measuring apparatus of a living body and method thereof
US8376946B2 (en) * 2002-05-16 2013-02-19 Barbara Ann Karamanos Cancer Institute Method and apparatus for combined diagnostic and therapeutic ultrasound system incorporating noninvasive thermometry, ablation control and automation
US20060100489A1 (en) * 2002-06-25 2006-05-11 Glucon, Inc. Method and apparatus for determining tissue viability
WO2004006755A3 (en) * 2002-07-16 2004-04-29 Alfred E Mann Inst Biomed Eng Support bra for ultrasonic breast scanner
US20040068180A1 (en) * 2002-10-04 2004-04-08 Jeffrey Collins Rotary ultrasound scanner for soft tissue examination
US6823736B1 (en) * 2002-11-20 2004-11-30 The United States Of America As Represented By The Secretary Of The Navy Nondestructive acoustic emission testing system using electromagnetic excitation and method for using same
JP4656809B2 (en) * 2002-12-24 2011-03-23 オリンパス株式会社 Photoacoustic signal detection head and the detection device having the same
WO2004062467A3 (en) * 2002-12-31 2004-09-16 John Herbert Cafarella Multi-sensor breast tumor detection
US6984211B2 (en) * 2003-01-03 2006-01-10 Mayo Foundation For Medical Education And Research Detection of tumor halos in ultrasound images
WO2004096082A3 (en) * 2003-04-24 2004-12-29 Rinat O Esenaliev Noninvasive blood analysis by optical probing of the veins under the tongue
US7850613B2 (en) * 2003-05-30 2010-12-14 Orison Corporation Apparatus and method for three dimensional ultrasound breast imaging
EP1635696A2 (en) * 2003-06-09 2006-03-22 Glucon Inc. Wearable glucometer
JP4406226B2 (en) * 2003-07-02 2010-01-27 株式会社東芝 The biological information imaging apparatus
US20050054906A1 (en) * 2003-09-08 2005-03-10 Joseph Page Spatial detectors for in-vivo measurement of bio chemistry
US20050070803A1 (en) * 2003-09-30 2005-03-31 Cullum Brian M. Multiphoton photoacoustic spectroscopy system and method
JP4643153B2 (en) * 2004-02-06 2011-03-02 東芝メディカルシステムズ株式会社 Non-invasive subject-information imaging apparatus
US8529449B2 (en) * 2004-03-15 2013-09-10 General Electric Company Method and system of thermoacoustic computed tomography
WO2006025940B1 (en) * 2004-06-30 2006-11-16 Univ Rochester Photodynamic therapy with spatially resolved dual spectroscopic monitoring
DE502005003761D1 (en) * 2004-07-20 2008-05-29 Univ Innsbruck Thermoakustisches tomographieverfahren und thermoakustischer tomograph
US8016758B2 (en) * 2004-10-30 2011-09-13 Sonowise, Inc. User interface for medical imaging including improved pan-zoom control
US8287455B2 (en) * 2004-10-30 2012-10-16 Sonowise, Inc. Synchronized power supply for medical imaging
US7771355B2 (en) * 2004-10-30 2010-08-10 Sonowise, Inc. System and method for medical imaging with robust mode switching via serial channel
US20060184042A1 (en) * 2005-01-22 2006-08-17 The Texas A&M University System Method, system and apparatus for dark-field reflection-mode photoacoustic tomography
US7708691B2 (en) * 2005-03-03 2010-05-04 Sonowise, Inc. Apparatus and method for real time 3D body object scanning without touching or applying pressure to the body object
US8042209B2 (en) * 2005-04-13 2011-10-25 University Of Maryland Techniques for compensating movement of a treatment target in a patient
US8747382B2 (en) 2005-04-13 2014-06-10 University Of Maryland, Baltimore Techniques for compensating movement of a treatment target in a patient
US7495369B2 (en) 2005-05-26 2009-02-24 Araz Yacoubian Broadband imager
JP2006326223A (en) * 2005-05-30 2006-12-07 Nippon Telegr & Teleph Corp <Ntt> Constituent concentration measuring device
US20070038117A1 (en) * 2005-07-26 2007-02-15 Bala John L Multi-spectral imaging endoscope system
US20070083110A1 (en) * 2005-10-09 2007-04-12 Sonowise, Inc. Programmable phase velocity in an ultrasonic imaging system
EP2668899B1 (en) * 2005-11-09 2015-07-29 Japan Science and Technology Agency Method of and apparatus for measuring properties of an object with acoustically induced electromagnetic waves
US20090054763A1 (en) * 2006-01-19 2009-02-26 The Regents Of The University Of Michigan System and method for spectroscopic photoacoustic tomography
WO2007084981A3 (en) * 2006-01-19 2007-11-29 David Chamberland System and method for photoacoustic imaging and monitoring of laser therapy
US9439571B2 (en) * 2006-01-20 2016-09-13 Washington University Photoacoustic and thermoacoustic tomography for breast imaging
US20070282404A1 (en) * 2006-04-10 2007-12-06 University Of Rochester Side-firing linear optic array for interstitial optical therapy and monitoring using compact helical geometry
CN100456016C (en) 2006-05-30 2009-01-28 华南师范大学 Multi-channel electronic parallel scanning photoacoustic real-time tomo graphic-imaging method and apparatus thereof
WO2007148239A3 (en) * 2006-06-23 2008-02-21 Michael Burcher Timing controller for combined photoacoustic and ultrasound imager
US20080119735A1 (en) * 2006-11-20 2008-05-22 Sonowise, Inc. Ultrasound imaging system and method with offset alternate-mode line
US20080123083A1 (en) * 2006-11-29 2008-05-29 The Regents Of The University Of Michigan System and Method for Photoacoustic Guided Diffuse Optical Imaging
EP1935346A1 (en) 2006-12-21 2008-06-25 Stichting voor de Technische Wetenschappen Imaging apparatus and method
US20080173093A1 (en) * 2007-01-18 2008-07-24 The Regents Of The University Of Michigan System and method for photoacoustic tomography of joints
US20080221647A1 (en) * 2007-02-23 2008-09-11 The Regents Of The University Of Michigan System and method for monitoring photodynamic therapy
US20080228073A1 (en) * 2007-03-12 2008-09-18 Silverman Ronald H System and method for optoacoustic imaging of peripheral tissues
WO2008137737A3 (en) * 2007-05-02 2009-01-08 Univ Rochester Feedback-controlled method for delivering photodynamic therapy and related instrumentation
US8870771B2 (en) 2007-05-04 2014-10-28 Barbara Ann Karmanos Cancer Institute Method and apparatus for categorizing breast density and assessing cancer risk utilizing acoustic parameters
JP4739363B2 (en) * 2007-05-15 2011-08-03 キヤノン株式会社 Biological information imaging apparatus, imaging method analysis method, and biometric information of the biological information
EP2003472A1 (en) * 2007-05-25 2008-12-17 Philips Electronics N.V. Ultrasound device with improved isotropy of the spatial resolution pattern
JP5349839B2 (en) * 2007-06-22 2013-11-20 キヤノン株式会社 Biological information imaging apparatus
US20090005685A1 (en) * 2007-06-29 2009-01-01 Canon Kabushiki Kaisha Ultrasonic probe and inspection apparatus equipped with the ultrasonic probe
US8323201B2 (en) 2007-08-06 2012-12-04 Orison Corporation System and method for three-dimensional ultrasound imaging
EP3229010A3 (en) 2007-10-25 2018-01-10 Washington University in St. Louis Confocal photoacoustic microscopy with optical lateral resolution
FR2923612B1 (en) * 2007-11-12 2011-05-06 Super Sonic Imagine Insonification device comprising a three-dimensional array of emitters arranged in a suitable spiral generating a FOCUSED wave beam of high intensity
EP2231018A4 (en) * 2007-12-12 2012-11-21 Jeffrey J L Carson Three-dimensional photoacoustic imager and methods for calibrating an imager
EP2110076A1 (en) * 2008-02-19 2009-10-21 Helmholtz Zentrum München Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH) Method and device for near-field dual-wave modality imaging
US8107710B2 (en) * 2008-05-23 2012-01-31 University Of Rochester Automated placental measurement
JP5159803B2 (en) * 2008-06-18 2013-03-13 キヤノン株式会社 Object information acquiring apparatus
JP2013173060A (en) * 2008-06-18 2013-09-05 Canon Inc Ultrasonic probe, and photoacoustic-ultrasonic system and inspection object imaging apparatus including ultrasonic probe
JP5294998B2 (en) 2008-06-18 2013-09-18 キヤノン株式会社 Ultrasound probe, the photoacoustic-ultrasonic system and the specimen imaging apparatus equipped with the ultrasonic probe
US8353833B2 (en) * 2008-07-18 2013-01-15 University Of Rochester Low-cost device for C-scan photoacoustic imaging
CN102137618B (en) 2008-07-25 2015-06-17 健康与环境慕尼黑德国研究中心赫姆霍茨中心(有限公司) Quantitative multi-spectral opto-acoustic tomography (MSOT) of tissue biomarkers
US8426933B2 (en) * 2008-08-08 2013-04-23 Araz Yacoubian Broad spectral band sensor
JP5419404B2 (en) 2008-09-04 2014-02-19 キヤノン株式会社 Light acoustic device
JP5451014B2 (en) * 2008-09-10 2014-03-26 キヤノン株式会社 Light acoustic device
CA2736868A1 (en) * 2008-09-10 2010-03-18 Endra, Inc. A photoacoustic imaging device
CN102264304B (en) * 2008-10-15 2014-07-23 罗切斯特大学 Photoacoustic imaging using versatile acoustic lens
US9528966B2 (en) * 2008-10-23 2016-12-27 Washington University Reflection-mode photoacoustic tomography using a flexibly-supported cantilever beam
JP5241465B2 (en) 2008-12-11 2013-07-17 キヤノン株式会社 Photoacoustic imaging apparatus and the photoacoustic imaging method
JP5641723B2 (en) 2008-12-25 2014-12-17 キヤノン株式会社 Object information acquiring apparatus
US9351705B2 (en) 2009-01-09 2016-05-31 Washington University Miniaturized photoacoustic imaging apparatus including a rotatable reflector
JP5275830B2 (en) * 2009-01-26 2013-08-28 富士フイルム株式会社 Optical ultrasonic tomographic imaging apparatus and an optical tomographic imaging methods
JP4723006B2 (en) * 2009-03-18 2011-07-13 オリンパス株式会社 Photoacoustic signal detection head and the detection device having the same
EP2422185A4 (en) * 2009-04-20 2013-02-13 Univ Missouri Photoacoustic detection of analytes in solid tissue and detection system
CA2760691A1 (en) * 2009-05-01 2010-11-04 Visualsonics Inc. System for photoacoustic imaging and related methods
WO2011000389A1 (en) 2009-06-29 2011-01-06 Helmholtz Zentrum München Deutsches Forschungszentrum Für Gesundheit Und Umwelt (Gmbh) Thermoacoustic imaging with quantitative extraction of absorption map
JP5525787B2 (en) * 2009-09-14 2014-06-18 株式会社東芝 The biological information imaging apparatus
US9057695B2 (en) * 2009-09-24 2015-06-16 Canon Kabushiki Kaisha Apparatus and method for irradiating a scattering medium with a reconstructive wave
JP5692988B2 (en) 2009-10-19 2015-04-01 キヤノン株式会社 Acoustic wave measuring apparatus
JP5424846B2 (en) * 2009-12-11 2014-02-26 キヤノン株式会社 Photoacoustic imaging apparatus
JP5538856B2 (en) * 2009-12-11 2014-07-02 キヤノン株式会社 Light acoustic device
JP5448785B2 (en) 2009-12-18 2014-03-19 キヤノン株式会社 Measuring apparatus, the movement control method, and program
JP5586977B2 (en) * 2010-02-08 2014-09-10 キヤノン株式会社 Object information acquiring apparatus and the method for obtaining subject information
JP2013519455A (en) 2010-02-12 2013-05-30 デルフィヌス メディカル テクノロジーズ,インコーポレイテッドDelphinus Medical Technologies,Inc. Way to characterize the patient's tissue
CN102843959B (en) * 2010-02-12 2014-11-12 戴尔菲纳斯医疗科技公司 Method of characterizing the pathological response of tissue to a treatmant plan
JP5645421B2 (en) 2010-02-23 2014-12-24 キヤノン株式会社 Ultrasound imaging device and a delay control method
JP5495882B2 (en) * 2010-03-25 2014-05-21 キヤノン株式会社 measuring device
JP5675142B2 (en) 2010-03-29 2015-02-25 キヤノン株式会社 Object information acquiring apparatus, subject information obtaining method, and a program for executing the method for obtaining subject information
JP5709399B2 (en) * 2010-04-02 2015-04-30 キヤノン株式会社 An object information acquiring apparatus and a control method thereof, and program
US9086365B2 (en) 2010-04-09 2015-07-21 Lihong Wang Quantification of optical absorption coefficients using acoustic spectra in photoacoustic tomography
JP5721477B2 (en) * 2010-04-22 2015-05-20 キヤノン株式会社 measuring device
JP5761935B2 (en) * 2010-07-22 2015-08-12 キヤノン株式会社 Object information acquiring apparatus, subject information obtaining method and object information acquisition program
JP5627328B2 (en) 2010-07-28 2014-11-19 キヤノン株式会社 Photoacoustic diagnostic apparatus
JP5364675B2 (en) * 2010-10-25 2013-12-11 オリンパス株式会社 Photoacoustic signal detection method
GB201018413D0 (en) 2010-11-01 2010-12-15 Univ Cardiff In-vivo monitoring with microwaves
US8817255B2 (en) 2010-12-17 2014-08-26 Canon Kabushiki Kaisha Apparatus and method for irradiating a scattering medium
US8976433B2 (en) 2010-12-17 2015-03-10 Canon Kabushiki Kaisha Apparatus and method for irradiating a scattering medium
US8954130B2 (en) 2010-12-17 2015-02-10 Canon Kabushiki Kaisha Apparatus and method for irradiating a medium
JP5939786B2 (en) * 2011-02-10 2016-06-22 キヤノン株式会社 Acoustic wave acquiring apparatus
JP5744557B2 (en) 2011-02-10 2015-07-08 キヤノン株式会社 Acoustic wave acquiring apparatus
US8997572B2 (en) 2011-02-11 2015-04-07 Washington University Multi-focus optical-resolution photoacoustic microscopy with ultrasonic array detection
RU2486501C2 (en) * 2011-02-28 2013-06-27 Александр Алексеевич Карабутов Laser optical-acoustic tomography method and apparatus for realising said method (versions)
US20140058245A1 (en) * 2011-04-08 2014-02-27 Canon Kabushiki Kaisha Measuring apparatus
US9304490B2 (en) 2011-05-27 2016-04-05 Canon Kabushiki Kaisha Apparatus and method for irradiating a medium
WO2013011869A1 (en) * 2011-07-20 2013-01-24 国立大学法人東京農工大学 Property measuring device for object to be measured and property measuring method for object to be measured
US8843190B2 (en) * 2011-07-21 2014-09-23 The Board Of Trustees Of The Leland Stanford Junior University Medical screening and diagnostics based on air-coupled photoacoustics
JP5818582B2 (en) 2011-08-30 2015-11-18 キヤノン株式会社 Object information acquiring apparatus and the method for obtaining subject information
WO2013046437A1 (en) * 2011-09-30 2013-04-04 キヤノン株式会社 Test object information-acquiring apparatus
JP2013078463A (en) 2011-10-04 2013-05-02 Canon Inc Acoustic wave acquiring apparatus
JP5950538B2 (en) * 2011-10-26 2016-07-13 キヤノン株式会社 Object information acquiring apparatus
JP2015500064A (en) * 2011-12-01 2015-01-05 オプトソニックス・インコーポレイテッド Photoacoustic tomography of the breast tissue using a hemispherical array and a flatbed scanning
JP6146955B2 (en) * 2012-03-13 2017-06-14 キヤノン株式会社 Device, display control method, and program
JP2013215236A (en) * 2012-04-04 2013-10-24 Canon Inc Subject information obtaining apparatus and subject information obtaining method
US9907540B2 (en) * 2012-06-11 2018-03-06 Empire Technology Development Llc Tissue liquid detection system
US9763641B2 (en) 2012-08-30 2017-09-19 Delphinus Medical Technologies, Inc. Method and system for imaging a volume of tissue with tissue boundary detection
JP6025513B2 (en) * 2012-11-12 2016-11-16 キヤノン株式会社 Object information acquiring apparatus and a control method thereof
EP2740410B1 (en) * 2012-12-04 2018-05-16 Canon Kabushiki Kaisha Subject information acquisition device, method for controlling subject information acquisition device, and program therefor
EP2742853A1 (en) 2012-12-11 2014-06-18 Helmholtz Zentrum München Deutsches Forschungszentrum für Gesundheit und Umwelt GmbH Handheld device and method for volumetric real-time optoacoustic imaging of an object
EP2754388A1 (en) 2013-01-15 2014-07-16 Helmholtz Zentrum München Deutsches Forschungszentrum für Gesundheit und Umwelt GmbH System and method for quality-enhanced high-rate optoacoustic imaging of an object
JP6192297B2 (en) * 2013-01-16 2017-09-06 キヤノン株式会社 Subject information obtaining apparatus, display control method, and program
KR20140126064A (en) * 2013-04-22 2014-10-30 한국전자통신연구원 Apparatus and method of self check for abnormal breast
JP5680141B2 (en) * 2013-05-23 2015-03-04 キヤノン株式会社 The method of the subject information obtaining apparatus and the object information acquiring apparatus
WO2015034879A3 (en) 2013-09-04 2015-04-30 Canon Kabushiki Kaisha Photoacoustic apparatus
JP6223129B2 (en) 2013-10-31 2017-11-01 キヤノン株式会社 Subject information obtaining apparatus, a display method, subject information obtaining method, and a program
US9730589B2 (en) 2013-10-31 2017-08-15 Canon Kabushiki Kaisha Examined-portion information acquisition apparatus
US20150119680A1 (en) 2013-10-31 2015-04-30 Canon Kabushiki Kaisha Subject information obtaining apparatus
EP2868279A1 (en) 2013-10-31 2015-05-06 Canon Kabushiki Kaisha Subject information acquisition apparatus
JP5766273B2 (en) * 2013-12-26 2015-08-19 キヤノン株式会社 measuring device
US20160007859A1 (en) * 2014-03-03 2016-01-14 The Board Of Trustees Of The Leland Stanford Junior University Coherent Frequency-Domain Microwave-Induced ThermoAcoustic Imaging
CN103829961A (en) * 2014-03-21 2014-06-04 南京大学 Multi-mode photoacoustic imaging method combined with limited angle X ray imaging and ultrasonic imaging
JP2015205136A (en) 2014-04-23 2015-11-19 キヤノン株式会社 Photoacoustic device, method for controlling photoacoustic device, and program
JP6308863B2 (en) 2014-05-14 2018-04-11 キヤノン株式会社 Photoacoustic apparatus, signal processing method, and program
US20150327770A1 (en) 2014-05-14 2015-11-19 Canon Kabushiki Kaisha Photoacoustic apparatus
JP2015216983A (en) * 2014-05-14 2015-12-07 キヤノン株式会社 Photoacoustic apparatus
JP2016013421A (en) 2014-06-13 2016-01-28 キヤノン株式会社 Photoacoustic device, signal processing device, and program
EP2957221A1 (en) 2014-06-20 2015-12-23 Canon Kabushiki Kaisha Object information acquiring apparatus
JP2016007500A (en) * 2014-06-26 2016-01-18 キヤノン株式会社 Object information acquiring apparatus
JP2017529913A (en) 2014-09-05 2017-10-12 キヤノン株式会社 Light acoustic device
JP5932932B2 (en) * 2014-10-02 2016-06-08 キヤノン株式会社 Light acoustic device
WO2016076244A1 (en) 2014-11-10 2016-05-19 Canon Kabushiki Kaisha Object information acquiring apparatus
JP6012776B2 (en) * 2015-01-08 2016-10-25 キヤノン株式会社 The method of the subject information obtaining apparatus and the object information acquiring apparatus
US20160213259A1 (en) * 2015-01-27 2016-07-28 Canon Kabushiki Kaisha Object information acquiring apparatus
JP5892639B1 (en) * 2015-03-06 2016-03-23 株式会社Murakumo Ultrasonic oscillation device
CN104887272B (en) * 2015-06-26 2017-09-19 四川大学 The ultrasonic wave imaging thermally induced excitation source and image forming apparatus configured
JP2017029277A (en) * 2015-07-30 2017-02-09 キヤノン株式会社 Photoacoustic apparatus, photoacoustic apparatus control method, and analyte holding member for photoacoustic apparatus
US20170067994A1 (en) 2015-09-04 2017-03-09 Canon Kabushiki Kaisha Transducer array, and acoustic wave measurement apparatus
GB201613879D0 (en) * 2016-08-12 2016-09-28 Micrima Ltd A medical imaging system and method
JP6324456B2 (en) * 2016-09-20 2018-05-16 キヤノン株式会社 The biological information acquisition device
US9888880B1 (en) 2017-08-01 2018-02-13 Endra Life Sciences Inc. Method and system for estimating fractional fat content of an object
US9888879B1 (en) 2017-08-01 2018-02-13 Endra Life Sciences Inc. Method and system for estimating fractional fat content of an object

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4255971A (en) * 1978-11-01 1981-03-17 Allan Rosencwaig Thermoacoustic microscopy
US4267732A (en) * 1978-11-29 1981-05-19 Stanford University Board Of Trustees Acoustic microscope and method
US4874251A (en) * 1984-04-04 1989-10-17 Wayne State University Thermal wave imaging apparatus
US5170666A (en) * 1991-03-29 1992-12-15 Larsen Lawrence E Nondestructive evaluation of composite materials using acoustic emissions stimulated by absorbed microwave/radiofrequency energy
US5657754A (en) * 1995-07-10 1997-08-19 Rosencwaig; Allan Apparatus for non-invasive analyses of biological compounds

Family Cites Families (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3603303A (en) 1968-10-08 1971-09-07 Cornell Res Foundation Inc Sonic inspection method and apparatus
US4059010A (en) * 1973-10-01 1977-11-22 Sachs Thomas D Ultrasonic inspection and diagnosis system
DE2643126A1 (en) 1975-09-26 1977-03-31 Leitgeb Norbert Ultrasonic diagnostic detector system - has steerable reflector consisting of dish with multiple detectors for target location
DE2705221C2 (en) * 1976-02-09 1986-07-17 Westbeck Navitele Ab, Stockholm, Se
US4233988A (en) * 1978-07-05 1980-11-18 Life Instruments Corporation High resolution rotating head ultrasonic scanner
US4206763A (en) 1978-08-01 1980-06-10 Drexel University Ultrasonic scanner for breast cancer examination
US4222274A (en) * 1978-09-15 1980-09-16 Johnson Steven A Ultrasound imaging apparatus and method
CA1137210A (en) * 1979-04-26 1982-12-07 Francis S. Foster Ultrasonic imaging method and device using one transducer having a line focus aligned with another transducer
US4246784A (en) * 1979-06-01 1981-01-27 Theodore Bowen Passive remote temperature sensor system
US4485819A (en) 1980-01-21 1984-12-04 Wolfgang Igl Mechanical accessory for commercially available compound apparatuses for echo mammography
US4385634A (en) * 1981-04-24 1983-05-31 University Of Arizona Foundation Radiation-induced thermoacoustic imaging
WO1983000009A1 (en) * 1981-06-22 1983-01-06 Whiting, James, Francis Improvements in or relating to ultrasound tomography
US4545385A (en) 1982-03-23 1985-10-08 Siemens Aktiengesellschaft Ultrasound examination device for scanning body parts
US4484820A (en) * 1982-05-25 1984-11-27 Therma-Wave, Inc. Method for evaluating the quality of the bond between two members utilizing thermoacoustic microscopy
US4481821A (en) * 1983-08-08 1984-11-13 The Charles Stark Draper Laboratory, Inc. Electro-elastic self-scanning crack detector
US4515017A (en) * 1983-11-21 1985-05-07 Advanced Technology Laboratories, Inc. Oscillating ultrasound scanhead
JPH074366B2 (en) * 1984-02-03 1995-01-25 株式会社東芝 Medical ultrasound device for the water tank
GB8619579D0 (en) * 1986-08-12 1986-09-24 Fulmer Res Inst Ltd Ultrasonic investigation apparatus
GB8727875D0 (en) 1987-11-27 1987-12-31 Cogent Ltd Ultrasonic probe
JPH0827264B2 (en) * 1988-09-21 1996-03-21 工業技術院長 Photoacoustic imaging method of the multi-modulation frequency
DE3925312A1 (en) * 1988-10-03 1990-04-05 Jenoptik Jena Gmbh Microscopic imaging appts. for thermal and thermo-elastic structure - has piezoelectrical flexural transducer detecting mechanical vibrations caused by light variations
US4950897A (en) * 1989-01-04 1990-08-21 University Of Toronto Innovations Foundation Thermal wave sub-surface defect imaging and tomography apparatus
US5348002A (en) * 1992-04-23 1994-09-20 Sirraya, Inc. Method and apparatus for material analysis
US5285260A (en) * 1992-07-06 1994-02-08 General Electric Company Spectroscopic imaging system with ultrasonic detection of absorption of modulated electromagnetic radiation
US5402786A (en) * 1992-09-11 1995-04-04 James E. Drummond Magneto-acoustic resonance imaging
US5840023A (en) * 1996-01-31 1998-11-24 Oraevsky; Alexander A. Optoacoustic imaging for medical diagnosis
US5615675A (en) * 1996-04-19 1997-04-01 Regents Of The University Of Michigan Method and system for 3-D acoustic microscopy using short pulse excitation and 3-D acoustic microscope for use therein
US5713356A (en) * 1996-10-04 1998-02-03 Optosonics, Inc. Photoacoustic breast scanner

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4255971A (en) * 1978-11-01 1981-03-17 Allan Rosencwaig Thermoacoustic microscopy
US4267732A (en) * 1978-11-29 1981-05-19 Stanford University Board Of Trustees Acoustic microscope and method
US4874251A (en) * 1984-04-04 1989-10-17 Wayne State University Thermal wave imaging apparatus
US5170666A (en) * 1991-03-29 1992-12-15 Larsen Lawrence E Nondestructive evaluation of composite materials using acoustic emissions stimulated by absorbed microwave/radiofrequency energy
US5657754A (en) * 1995-07-10 1997-08-19 Rosencwaig; Allan Apparatus for non-invasive analyses of biological compounds

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP0942683A4 *

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002015776A1 (en) 2000-08-24 2002-02-28 Glucon Inc. Photoacoustic assay and imaging system
US6846288B2 (en) 2000-08-24 2005-01-25 Glucon Inc. Photoacoustic assay and imaging system
EP1700563A2 (en) 2000-08-24 2006-09-13 Glucon Inc. Photoacoustic assay and imaging system
US7646484B2 (en) 2002-10-07 2010-01-12 Intellidx, Inc. Method and apparatus for performing optical measurements of a material
US8332006B2 (en) 2004-05-06 2012-12-11 Nippon Telegraph And Telephone Corporation Constituent concentration measuring apparatus and constituent concentration measuring apparatus controlling method
US9008742B2 (en) 2004-05-06 2015-04-14 Nippon Telegraph And Telephone Corporation Constituent concentration measuring apparatus and constituent concentration measuring apparatus controlling method
US9060691B2 (en) 2004-05-06 2015-06-23 Nippon Telegraph And Telephone Corporation Constituent concentration measuring apparatus and constituent concentration measuring apparatus controlling method
US9198580B2 (en) 2004-05-06 2015-12-01 Nippon Telegraph And Telephone Corporation Constituent concentration measuring apparatus and constituent concentration measuring apparatus controlling method
US8920321B2 (en) 2008-06-18 2014-12-30 Canon Kabushiki Kaisha Photoacoustic imaging apparatus
US8814794B2 (en) 2009-12-17 2014-08-26 Canon Kabushiki Kaisha Measuring system, image forming method, and program
US9924876B2 (en) 2013-03-29 2018-03-27 Canon Kabushiki Kaisha Object information acquiring apparatus and method of controlling same

Also Published As

Publication number Publication date Type
EP0942683B1 (en) 2008-09-17 grant
JP2001507952A (en) 2001-06-19 application
CA2187701A1 (en) 1998-04-04 application
US20020035327A1 (en) 2002-03-21 application
US5713356A (en) 1998-02-03 grant
EP0942683A4 (en) 1999-11-24 application
US6292682B1 (en) 2001-09-18 grant
EP0942683A1 (en) 1999-09-22 application
CA2187701C (en) 2008-12-09 grant
DE69738998D1 (en) 2008-10-30 grant
US6102857A (en) 2000-08-15 grant
JP4341987B2 (en) 2009-10-14 grant

Similar Documents

Publication Publication Date Title
Wang et al. Microwave-induced acoustic imaging of biological tissues
Xu et al. Time-domain reconstruction for thermoacoustic tomography in a spherical geometry
US4331021A (en) Contrast resolution tissue equivalent ultrasound test object
Zhu et al. Imager that combines near-infrared diffusive light and ultrasound
US6926672B2 (en) Electret acoustic transducer array for computerized ultrasound risk evaluation system
US4855911A (en) Ultrasonic tissue characterization
US6050943A (en) Imaging, therapy, and temperature monitoring ultrasonic system
Kruger Photoacoustic ultrasound
US5357964A (en) Doppler imaging device
US6500121B1 (en) Imaging, therapy, and temperature monitoring ultrasonic system
US5615675A (en) Method and system for 3-D acoustic microscopy using short pulse excitation and 3-D acoustic microscope for use therein
Köstli et al. Temporal backward projection of optoacoustic pressure transients using Fourier transform methods
Madsen et al. Method of data reduction for accurate determination of acoustic backscatter coefficients
Xu et al. Photoacoustic imaging in biomedicine
Lizzi et al. Theoretical framework for spectrum analysis in ultrasonic tissue characterization
Oraevsky et al. Laser optoacoustic tomography for medical diagnostics: Principles
Kruger et al. Thermoacoustic CT with radio waves: A medical imaging paradigm
Ku et al. Scanning microwave‐induced thermoacoustic tomography: Signal, resolution, and contrast
Köstli et al. Two-dimensional photoacoustic imaging by use of Fourier-transform image reconstruction and a detector with an anisotropic response
Xu et al. Exact frequency-domain reconstruction for thermoacoustic tomography. II. Cylindrical geometry
Kruger et al. Thermoacoustic computed tomography using a conventional linear transducer array
US5305752A (en) Acoustic imaging device
US20110040176A1 (en) Method and device for near-field dual-wave modality imaging
Xu et al. Exact frequency-domain reconstruction for thermoacoustic tomography. I. Planar geometry
Montaldo et al. Coherent plane-wave compounding for very high frame rate ultrasonography and transient elastography

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AL AM AT AU AZ BA BB BG BR BY CA CH CN CU CZ DE DK EE ES FI GB GE GH HU ID IL IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MD MG MK MN MW MX NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT UA UG US UZ VN YU ZW AM AZ BY KG KZ MD RU TJ TM

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH KE LS MW SD SZ UG ZW AT BE CH DE DK ES FI FR GB GR IE IT LU MC

121 Ep: the epo has been informed by wipo that ep was designated in this application
ENP Entry into the national phase in:

Ref country code: JP

Ref document number: 1998 516884

Kind code of ref document: A

Format of ref document f/p: F

WWE Wipo information: entry into national phase

Ref document number: 1997944607

Country of ref document: EP

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

WWP Wipo information: published in national office

Ref document number: 1997944607

Country of ref document: EP

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
NENP Non-entry into the national phase in:

Ref country code: CA